Income Taxes - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Tax Disclosure [Abstract]
Income tax expense	$ 474	$ 105,447	$ 4,025	$ 113,115
Effective income tax rate			16.80%	(57.30%)